Automatic fire-alarm.



PATENTED MAY 22, 1906.

J. W. GRIFFIN.

AUTOMATIC FIRE ALARM.

APPLICATION rum) APR.10, 1905.

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r nu H m J "UNITED STATES PATENT OFFICE.

AUTOMATIC FIRE-ALARM.

Specification of Letters Patent.

Patented May 22, 1906.

Application filed April 10, 1905. Serial No. 254,739.

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Be it known that I, JOHN W. GRIFFIN, a citizen of the United States,residing at Pawtucket, in the county of Providence and State of RhodeIsland, have invented a new and useful Improvement in Automatic Fire-Alarms, of which the following is a specification.

This invention is in that. class of electric fire-alarms in which anopen circuit is maintained normally by a fusible cap. In the event offire the plug fuses and allows the previously-separated contact-pointsto move into engagement, thus closing the circuit and causing analarm-bell to ring.

My present invention seeks to provide an exceeding simple and cheapdevice having no exposed binding-posts, adjustingscrews, or other partsthat can be .surreptitiously tampered with or that can be accidentallymisplaced or otherwise rendered inoperative.

The drawings annexed hereto serve to illustrate my said invention.

Figure 1 is a perspective view of my newlyimproved device, and Fig. 2 isan under side plan view of the same. Fig. 3 is a longitudinal centralview of the base-section and shows in side elevation the cylindricalcasein which the contact-points are supported. Fig. 4 is a relativelyenlarged central sectional view of said case and of the parts locatedtherein, the contact-points being shown as separated. In Fig. 5 I haveshown by a similar view the contact-points as closed.

Referring to the drawings, the letter a indicates a base of porcelain orthe like suitable material, the upper face of said base being channeledor recessed, as at a, in order that 'the operative parts of my devicemay be partially inclosed and protected, as I shall explain more fullylater. The under side of said base is also,by preference, channeled, asata (1 in order that the binding-posts I) and nuts I) may be concealed,as well as the circuit-wiros c.

insulating material having fixedly mounted upon its opposite endsmetallic caps e 6, each of which caps is formed with an angular foot 6that is clamped to the base a by means of the binding-posts b, as willbe clearly understood by reference to Figs. 3 and 4 of the drawings.

The tubular section CZ lies partly within the recess a, this arrangementof base and tube being specially designed to protect the tube fromaccidental disarrangement or injury.

The cap 6 is perforated centrally to receive and support the outer endportion of a rod or tube 9, that is slidably mounted within the tube (1.The inner end of said rod g is formed with an enlargement or head g.

The letter it indicates a spiral spring. that is coiled loosely upon therod g, one end of said spring abutting the head 9 and the other endabutting the inner face of the cap 6. (See Fig. 4.) The said spring actswith a constant tendency to expand, and thus force the rod 9 fartherwithin the tube dthat is to say, toward the cap eand thus cause theheaded end of the rod to contact with certain spurs i, of thin metal,(preferably copper,) secured to or formed as a part of the inner face ofcap 6. The head g is cupped, as at 9 so that when the rod is forcedinward by the spring h the cap will inclose the said spurs and bend themtoward each other, as seen in Fig. 5, thus providing a scrapingconnection that will insure a perfect contacting of the engagingmetallic parts, even ifsaid parts were corroded, greased, or otherwisecoated by foreign substance.

In order to hold the rod 9 and spurs i. apart, and thus maintainnormally an open circuit, I secure upon the outwardly-projecting end ofsaid rod, by means of readily-fusible solder,

a cap or sleeve is, o1 thin metal, and, by prefer ence, I perforate thecircumferential shell of said sleeve is, as at k, so that the solder mayfill said holes, and thus serve, in effect, to rivet the sleeve to therod and hold the parts securely to ether. The said perforations alsoenable a ame to reach the soldered joint and fuse the solder morereadily and effectively than if a non-perforated cap or sleeve wereused.So soon as the solder fuses and the sleeve 1c is loosened the spring itshoots the rod g inward and moves the cupped head g into contact withthe spurs 1', thus closing the electric circuit and causing analarm-bell to ring. The letter (1 denotes a tubular section of Mydescribed device is of simple and cheap construction and may be of suchsmall size and pleasing design that it may be used in residences and thelike places where the more elaborate and unsightly devices would beconupon the opposite face having longitudinal and transverseintersecting channels, bindingposts, nuts and circuit-Wires connected inthe last-named channels, a tubular section of insulating material in thefirst-mentioned channel, caps on said section having feet held by saidbinding-posts, a fixed contact Within said tubular section, a movablecontact within said section, and fusible means for normally holding saidcontacts separated.

2. In an automatic fire-alarm, a tubular section of insulating material,a fixed contact therein, a spring-actuated contact in said section, arod carrying said movable contact with one end extended through saidsection, and a perforated sleeve outside said section and receiving theextended end of said rod and held to the latter by fusible materialfilling said perforations.

3. In an automatic fire-alarm, a tubular section of insulating material,a fixed contact therein, a spring-actuated contact in said section, arod carrying said movable contact with one end extended through saidsection, and a perforated sleeve outside said section and receiving theextended end of said rod and held to the latter by fusible materialfilling said perforations, said perforations being distributed about thesaid sleeve, and the sleeve bearing against the end of the tubularsection.

In testimony whereof I have signed my name to this specification in thepresence of tWo subscribing Witnesses.

JOHN W GRIFFIN. Witnesses:

C. F. HARRIs, ALoNzo R. WVILLIAMs.

